linux-kernel - Re: [PATCH v2] clk: rockchip: reset init state before mmc card initialization

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Message-ID: <4930263.TgyPa9P2vP@phil>
Date:	Thu, 03 Sep 2015 21:07:34 +0200
From:	Heiko Stuebner <heiko@...ech.de>
To:	Shawn Lin <shawn.lin@...k-chips.com>
Cc:	Stephen Boyd <sboyd@...eaurora.org>,
	Michael Turquette <mturquette@...libre.com>,
	linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] clk: rockchip: reset init state before mmc card initialization

Am Dienstag, 25. August 2015, 08:34:36 schrieb Shawn Lin:
> mmc host controller's IO input/output timing is unpredictable if
> bootloader execute tuning for HS200 mode. It might make kernel failed
> to initialize mmc card in identification mode. The root cause is
> tuning phase and degree setting for HS200 mode in bootloader aren't
> applicable to that of identification mode in kernel stage. Anyway, we
> can't force all bootloaders to reset tuning phase and degree setting
> before into kernel. Simply reset it in rockchip_clk_register_mmc.
> 
> Signed-off-by: Shawn Lin <shawn.lin@...k-chips.com>

I'm not 100% sure why you need the new function instead of having that 
directly in rockchip_clk_register_mmc, but I guess that is a matter of taste 
and I don't have a hard opinion on that, so

Reviewed-by: Heiko Stuebner <heiko@...ech.de>

> 
> ---
> 
> Changes in v2:
> - rename to rockchip_clk_mmc_reset
> - simplifying the code
> 
>  drivers/clk/rockchip/clk-mmc-phase.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/clk/rockchip/clk-mmc-phase.c
> b/drivers/clk/rockchip/clk-mmc-phase.c index e9f8df32..1d3e8fe6 100644
> --- a/drivers/clk/rockchip/clk-mmc-phase.c
> +++ b/drivers/clk/rockchip/clk-mmc-phase.c
> @@ -38,6 +38,8 @@ static unsigned long rockchip_mmc_recalc(struct clk_hw
> *hw, #define ROCKCHIP_MMC_DEGREE_MASK 0x3
>  #define ROCKCHIP_MMC_DELAYNUM_OFFSET 2
>  #define ROCKCHIP_MMC_DELAYNUM_MASK (0xff << ROCKCHIP_MMC_DELAYNUM_OFFSET)
> +#define ROCKCHIP_MMC_INIT_STATE_RESET 0x1
> +#define ROCKCHIP_MMC_INIT_STATE_SHIFT 1
> 
>  #define PSECS_PER_SEC 1000000000000LL
> 
> @@ -119,6 +121,14 @@ static const struct clk_ops rockchip_mmc_clk_ops = {
>  	.set_phase	= rockchip_mmc_set_phase,
>  };
> 
> +static void rockchip_clk_mmc_reset(struct rockchip_mmc_clock *mmc_clock)
> +{
> +	if (mmc_clock->shift == ROCKCHIP_MMC_INIT_STATE_SHIFT)
> +		writel(HIWORD_UPDATE(ROCKCHIP_MMC_INIT_STATE_RESET,
> +				     ROCKCHIP_MMC_INIT_STATE_RESET,
> +				     mmc_clock->shift), mmc_clock->reg);
> +}
> +
>  struct clk *rockchip_clk_register_mmc(const char *name,
>  				const char *const *parent_names, u8 num_parents,
>  				void __iomem *reg, int shift)
> @@ -139,6 +149,12 @@ struct clk *rockchip_clk_register_mmc(const char *name,
> mmc_clock->reg = reg;
>  	mmc_clock->shift = shift;
> 
> +	/*
> +	* Assert init_state to soft reset the CLKGEN
> +	* for mmc tuning phase and degree
> +	*/
> +	rockchip_clk_mmc_reset(mmc_clock);
> +
>  	if (name)
>  		init.name = name;

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